Grapeshot, you're not the first. I was just reading recently(Not sure where, maybe on Gunboards) that during WW2, when reloading compomnents were even harder to come by than they are now, Surplus 30-40 was readily available. So they would break them down for components, to reload other calibers, and for .303 they would just trim the neck a bit and reload them.
Curious, though...30-40 brass has a bevel on the rim, that 303 doesn't. I never looked, but I guess since it worked without the bevel, then the Krag bolt face must not require the bevel.